This invention relates generally to operator control panels which are illuminated.
Operator control panels such as the type used with the New Holland Model 2000 baler include membrane switches for remotely controlling various functions of the baler and liquid crystal displays for displaying important baling information. The membrane switches and the liquid crystal displays have been illuminated from behind, i.e., backlit, by an internal light source housed within the control panel. Backlighting of membrane switches in this manner is undesirable because the legends on the faces of the switches are very difficult to read in the dark. This is due to the fact that the grids inside the switches block some of the light emitted by the internal light source and thereby prevent adequate illumination of the switch legends. Also, backlighting of liquid crystal displays may be undesirable because it produces "hot spots" on the displays if the light source is directly behind the displays.
One possible solution to the aforementioned problem is the use of an additional external light source to illuminate the front of the operator panel. However, this is not desirable since two separate light sources (one internal and one external) would then be required thereby increasing the cost and complexity of the operator panel.
In one embodiment, the present invention provides an operator control panel including an enclosure defined by a back wall, side walls, a top wall, a bottom wall, and a front panel. Display means disposed inside the enclosure is viewable through a window in the front panel, and lamp means is also disposed inside the enclosure. First reflective means is located inside the enclosure, and second reflective means is located outside the enclosure. The lamp means is positioned so that light rays therefrom are projected onto the first reflective surface and then onto the display means while other light rays from the lamp means are projected onto the second reflective means and then onto the front panel. Preferably the first reflective means comprises a first reflective surface on the back wall of the enclosure, and the second reflective means comprises a second reflective surface on a forward extension of the top wall of the enclosure. The display means preferably comprises a liquid crystal display positioned such that the first-mentioned light rays are projected onto the back thereof.
In another embodiment of the present invention, the lamp means is disposed outside the enclosure of the operator control panel and the second reflective means is omitted. The lamp means is positioned so that light rays therefrom are projected onto reflective means located inside the enclosure and then onto the display means while other light rays from the lamp means are projected onto the front panel.